AQA A-Level Chemistry Paper 2 (7405/2) - 19th June 2023 [Exam Chat]

Can someone please help me with this question? I don't understand why the answer is

This was what someone posted earlier, took a ss then!

thank you so much! i forgot to take a ss and thought i'd lost it haha youre a lifesaver

for drawing mechanisms / calculations are we allowed to write in pencil? because im scared in mechanisms that ill make a mistake if i do it in pen

In the first version of reaction 2 it's showing a reaction with excess NH3.

The question states that reaction 2 is carried out under different conditions and it still produces a compound with Nitrogen so it has to be with excess alkane and NH3 is limiting so the alkane reacts with NH3 multiple times to make an N substituted compound.

The general rule is a reaction with an alkane and excess NH3 you get an amide.

A reaction with NH3 and excess alkane you get an N-substituted amide as the H on NH3 is substituted for the alkane.

It goes from a 1° to 2° to 3° amine and a further reaction can lead to 4° which is an ammonium salt.

However the compound can't be an ammonium salt as that has too many CH groups so it has to be a 3° amine as that's the only one that can make C9H21N

Hope this helps

I’m pretty sure pencil isn’t picked up but then someone will go through and mark it manually. Tbh I would do pen because I wouldn’t want to risk it. Maybe if you’re really unsure work it out with pencil and then write it out in pen? But it should be fine- I saw aqa post a tweet about this.

Pretty sure it says u can use pencil in the instructions but it’d have to be HB or something.

guys for paper 2 are there any practical heavy questions, ill be honest not touched practicals

During non seluctive reduction when butanal us reduced by H2 to butan-1-ol would the reaction be:

CH3CH2CH2CHO + H2 ---> CH3CH2CH2CH2OH

Or this?

CH3CH2CH2CHO + 2H2 --> CH3CH2CH2CH2OH

And if so, why isn't it the other one?

Due to the fact that there should be the same amount of everything on each side, the answer is the first one. (4C on each side for both, 1O on each side for both). Since there's 10H on the RHS, there has to be 10H on the LHS.

Anyone have any predictions?

for reduction of nitriles to amines can you say any from: 1. LiAlH4 + dry ether + dilute acid 2. Fe + HCl 3. Ni + H2 or is it just the 1st one?

Anyone have any predictions?

for the nucleophilic sub reaction with cyanide, should i write the reagents and conditions as KCN in alcohol/ethanoic solution or in alcohol and water? is it the same thing?? this q only allows alcohol and water.